1. Department of Gastroenterology; Tokyo Women's Medical University, Yachiyo Medical Center; 477-96 Owada-Shinden Yachiyo Chiba 276-8542 Japan
2. Department of Surgery, Gastrointestinal Surgery; Tokyo Women's Medical University, Yachiyo Medical Center; Chiba Japan
3. Department of Endoscopy; Tokyo Women's Medical University, Yachiyo Medical Center; Chiba Japan